This invention relates to a new process of forming heterocyclic compounds and their use in the preparation of asymmetrical cis- or trans-thiazine-indigo compounds. This invention also relates to a new process of forming new cis- or trans-thiazine-indigo compounds containing further heterocyclic or carbonamido moieties. This invention also relates to a process of converting the cis-thiazine-indigo compounds into the trans-thiazine-indigo isomers, which are known to be pigments.
Thiazine-indigo compounds are an important series of pigments. Prior art processes for forming these pigments involve the reaction of certain o-aminomercapto-carbocyclic or -heterocyclic compounds with maleic acid or a derivative thereof in the presence of a solvent. Solvents useful for this purpose were either a carboxylic acid (which also acted to catalyze the reaction) or an inert polar aprotic solvent.
Thus, in DE 2 151 723 a process is described for making symmetrically substituted benzothiazine-indigo compounds wherein substituted ortho-aminomercapto-carbocyclic or -heterocyclic compounds are reacted with a maleic acid derivative in a carboxylic acid, e.g. acetic acid. By symmetrically substituted is meant that there is identical substitution on each of the benzothiazine rings.
In DE-OS 253 61 20 a process is described for making other symmetrically substituted benzothiazine-indigo compounds wherein substituted ortho-aminothiophenols are reacted with a maleic acid derivative in an inert polar aprotic solvent. It is alleged that the benzothiazine-indigo compounds so formed display improved pigmentary properties, e.g. brighter and cleaner shade over the compounds made in a carboxylic acid solution. However, they can only be produced in poor yield.
An improved process of forming thiazine-indigo pigments is also described in the international application WO 98/32800 A1.
There still remains a need to provide a further improved process of forming thiazine-indigo compounds, especially trans-thiazine-indigo pigments.
Accordingly, the invention provides in one of its aspects an environmentally friendly water-based process for the preparation of thiazine-indigo compounds according to the formula (I) and (II) 
wherein R1 and R2 independently represent the atoms necessary to complete the formation of a substituted or unsubstituted aromatic or aliphatic carbocyclic or heterocyclic ring system and R3 is hydrogen, C1-12alkyl or phenyl, comprising the step of reacting in the presence of an aqueous system a compound of formula (Ia) resp. (Ib) 
with a compound of formula (IIa) 
in which formulae R1, R2 and R3 have the meaning indicated above; Hal is Cl or Br; R4 is hydrogen or a metallic ion selected from Na+, K+ or Zn2+ and R5 is a leaving group commonly used in substitution reactions at carbonyl carbon atoms.
The aqueous system comprises water or water and an acidic catalyst or water and a basic catalyst or a mixture of water and a with water miscible solvent, like alcohols.
Preferably the molar ratio of the reactants is 1:1.
The process is carried out in the presence of a carboxylic acid or of a salt thereof, e.g. acetic acid, or an inorganic acid or salt thereof, e.g. sulphuric acid or hydrochloric acid, which also acts as a catalyst, and an aqueous medium, e.g. water or a mixture of water and a miscible solvent, preferably an alcohol with 1-5 C-atoms, e.g. ethanol, methanol, butanol or another high boiling point alcohol.
The basic catalyst is an inorganic base, especially sodium or potassium hydroxide or an organic base such as triethylamine.
The reaction is preferably carried out in water in the presence of 0 to 95% by weight, preferably 10% by weight of an acid catalyst, e.g. acetic acid or hydrochloric acid or sulphuric acid or phosphoric acid.
The reaction temperature is preferably of the order of 0 to 150xc2x0 C., more preferably between 10 and 40xc2x0 C.
The leaving group in R5 is either hydroxy, chlorine or a C1-5alkoxy group.
A further aspect of the invention consists in the process for the preparation of partly new compounds of the formula (Ia) and (Ib) 
wherein the substituents R1, R2, R3, R5 and Hal have the meaning given above, comprising the reaction of a compound of formula (IIb) 
with a compound of formula (IIIa) or (IIIb) 
wherein Hal is Cl or Br and R5 is a leaving group commonly used in substitution reactions at carbonyl carbon atoms,
in the same aqueous system as described above.
Compounds of formula (II), (IIIa) and (IIIb) are known compounds or can be prepared in analogy to known methods.
The compound of formula (IV) 
is known and its preparation is described in Aust. J. Chem., 39, 503-510 (1986). However, the reaction is performed in organic solvents and the product was isolated in poor yield (28.8%) as a by-product.
The preparation of compound (IV) is also described in Helvetica Chem. Acta, 57 (8), 2664-78 (1974). Herein the reaction is carried out in glacial acetic acid.
The water based process of the invention is generally applicable and allows the preparation of other derivatives, in good yield.
The thiazine-indigo compounds of formula (I) or (II) may be symmetrically substituted, that is R1 and R2 are identical. Alternatively, they may be asymmetrically substituted, that is R1 and R2 are not identical. Non-identity refers to either the ring systems R1 and R2 being different or, in the event that the ring systems are identical, the substituents attached to the respective ring systems are different.
Preferred thiazine-indigo compounds formed according to the invention are those asymmetric compounds wherein R1 and R2 are independently selected from the group consisting of 
wherein Y is halogen which includes F, Cl and Br, especially Cl; R is C1-4alkyl, especially methyl or ethyl, aryl, ORxe2x80x2, SRxe2x80x2, NRxe2x80x2Rxe2x80x3 or CONRxe2x80x2Rxe2x80x3, where Rxe2x80x2 and Rxe2x80x3 are independently H, C1-18alkyl, C5-10cycloalkyl or aryl; a is 1, 2, 3 or 4 and b is 1, 2, 3 or 4.
More preferred thiazine-indigo compounds are those in which R1 consists of the atoms necessary to complete a benzene ring which is optionally substituted with, for example halogen or alkyl and R2 consists of the atoms necessary to complete a ring system which is an equally substituted benzene ring or a different ring system, e.g. naphthalene, pyridine or 1,4-benzodiazine.
The thiazine-indigo compounds formed according to the invention may be substituted on the ring systems with one or more of any of the non-water-solubilising substituents common in the art of pigments. Preferably the ring system substituents are selected from the group consisting of halogen, trifluoromethyl, nitro, cyano, carbonamide, alkyl, aryl, alkoxy, amino, alkylamino, thioalkyl, phenoxy, phenylamino, phenylthio, acyl, acyloxy or acylamino.
The term xe2x80x9chalogenxe2x80x9d includes fluorine and especially chlorine and bromine. The term xe2x80x9calkylxe2x80x9d or xe2x80x9calkoxyxe2x80x9d comprises preferably radicals with 1 to 4 carbon atoms. The terms xe2x80x9calkylaminoxe2x80x9d and xe2x80x9cphenylaminoxe2x80x9d include for example N,N-dialkylamino and N,N-diphenylamino as well as N-monoalkylamino and N-monophenylamino.
The aforementioned alkyl, alkoxy, phenyl and phenoxy substituents may themselves contain one or more substituents selected from the substituents hereinabove described.
Another category of preferred thiazine-indigo compounds according to the invention are those of the formulae (I) and (II) in which R1 and R2 represent the atoms necessary to complete the formation of a benzene ring which is part of a heterocyclic ring system and more specifically compounds of the formulae (Va) resp. (Vb), (VIa) resp. (VIb), (VIIa) resp. (VIIb) and (VIIIa) resp. (VIIIb) 
wherein R1 represents the atoms necessary to complete the formation of a substituted or unsubstituted aromatic or aliphatic carbocyclic or heterocyclic ring system; R3 is hydrogen, C1-12alkyl or phenyl; R6, Rxe2x80x26, R7 and Rxe2x80x27 are independently hydrogen, an alkyl or aryl group
which are novel compounds and can be prepared by a process comprising the step of reacting in the presence of an aqueous system a compound of formula (IXa) and/or (IXb) 
or a compound of formulae (Xa) and/or (Xb) 
wherein R4 and Rxe2x80x24 independently are H or a metallic ion selected from Na+, K+ or Zn2+ or a compound of formulae (IXa) or (Xa) and a compound of formula (IIb) 
with a compound of formula (IIIa) [cis-isomers] or (IIIb) [trans-isomers]
wherein Hal is Cl or Br and R5 is a leaving group commonly used in substitution reactions at carbonyl carbon atoms, e.g. Cl or C1-5alkoxy or OH.
The aqueous system comprises water or water and an acidic catalyst or water and a basic catalyst or a mixture of water and a with water miscible solvent, like alcohols.
Particularly interesting is the possibility to use dihalofumaric acids or dihalomaleic acids, already prepared or generated in situ.
It has been discovered that fumaric derivatives of formula (IIIb) give the trans-isomer of formula (VIIb) or (VIIIb) and the maleic derivatives of formula (IIa) give the cis-isomer of formula (VIIa) or (VIIIa).
Preferably the molar ratio of the reactants is 2:1 respectively 1:1:1 when different compounds of formula (IXa), (IXb) or (Xa), (Xb) are used.
The process is carried out in the presence of a carboxylic acid or salt thereof, e.g. acetic acid, or an inorganic acid or salt thereof, e.g. sulphuric acid or hydrochloric acid, which also acts as a catalyst, and an aqueous medium, e.g. water or a mixture of water and a miscible solvent, preferably an alcohol with 1-5 C-atoms, e.g. ethanol, methanol, butanol or another high boiling point alcohol.
The basic catalyst is an inorganic base, especially sodium or potassium hydroxide or an organic base such as triethylamine.
The reaction is preferably carried out in water in the presence of 0 to 95% by weight, preferably 10% by weight of an acid catalyst, e.g. acetic acid or hydrochloric acid or sulphuric acid or phosphoric acid.
The reaction temperature is preferably of the order of 0 to 150xc2x0 C., more preferably between 10 and 100xc2x0 C. The pressure is preferably of the order of 1 to 20 bars, more preferably between 1 and 10 bars.
A further group of novel compounds are compounds of the formulae (XI) and (XII) 
wherein R8 and R9 are independently H, C1-18alkyl, phenyl, naphthyl, C5-10cycloalkyl or 
Such compounds are prepared by the process according to the invention starting from the intermediates (XIII), (XIV) and (XV) 
wherein R8 and R9 are independently H, C1-18alkyl, phenyl, naphthyl, C5-10cycloalkyl or 
R4 is H or a metallic ion selected from Na+, K+ or Zn2+.
The compounds of formula (XIII) and (XIV), except for R8=R9=H, are new. They are prepared according to methods described in the literature (FR-patent 1443917). The compounds of formula (XIII) and (XIV) with R8=R9=H are already published in J. Polymer Sci. A-1, 6, (1968), 2939.
Reduction of compounds of formula (XIII) and (XIV) forms compounds of formula (XV). According to methods described in the literature the reagent for reduction can be zinc in acetic acid (J. Org. Chem. 31, (1966), 625), or zinc with aqueous hydrochloride acid in an alcohol (in analogy to Can. J. Chem, 48, (1965), 2612) or sodium sulfide or sodium hydrogen sulfide.
Alternatively, the compounds of the invention which are trans-isomers can be prepared by reacting the starting materials in an inert polar solvent in the presence or not of an acidic catalyst which can be a carboxylic acid, e.g. acetic acid or p-toluene sulfonic acid.
A further aspect of the invention is the process of converting the cis-isomers into the trans-isomers by thermal treatment in an inert polar solvent, in the presence or not of an acidic catalyst, that can be a carboxylic acid, e.g. acetic acid, or para-toluene sulfonic acid or another acid usually used in organic chemistry.
The inert polar solvent can be chlorobenzene, nitrobenzene, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, or a high boiling point alcohol, like ethylene glycol, dipropylene glycol methyl ether.
The cis-trans conversion can also be carried out in a mixture of water with a miscible alcohol at high temperature and under pressure.
The thermal treatment comprises temperatures of from 100 to 250xc2x0 C., preferably of from 100 to 180xc2x0 C., more preferably of from 130 to 160xc2x0 C., and pressures of from 1 to 60 bars, preferably of from 1 to 20 bars.
The trans-thiazine-indigo pigments formed by the conversion process according to the invention are suitable for the mass pigmentation of suitable substrates including synthetic polymers, synthetic resins and regenerated fibers optionally in the presence of solvents. These substrates more particularly include oil, water and solvent based surface coatings, polyester spinning melts, polyethylene, polystyrene and polyvinyl chloride molding materials, rubber and synthetic leather. Furthermore, the pigments can be used in the manufacture of printing inks, for the mass coloration of paper and for coating and printing textiles.
The trans-thiazine-indigo pigments are also suitable for cosmetic uses, like nail varnishes or make-up.
The trans-thiazine-indigo pigments are also suitable as colorants in electrophotographic toners and developers, such as one- or two-component powder toners (also called one- or two-component developers), magnetic toners, liquid toners, polymerization toners and specialty toners (literature: L. B. Schein, xe2x80x9cElectrophotography and Development Physicsxe2x80x9d; Springer Series in Electrophysics 14, Springer Verlag, 2nd Edition, 1992).
Typical toner binders are addition polymerization, polyaddition and polycondensation resins, such as styrene, styrene-acrylate, styrene-butadiene, acrylate, polyester and phenol-epoxy resins, polysulphones, polyurethanes, individually or in combination, and also polyethylene and polypropylene, which may comprise further constituents, such as charge control agents, waxes or flow assistants, or may be modified subsequently with these additives.
The trans-thiazine-indigo pigments are suitable, furthermore, as colorants in powders and powder coating materials, especially in triboelectrically or electrokinetically sprayable powder coating materials which are used for the surface coating of articles made, for example, from metal, wood, plastic, glass, ceramic, concrete, textile material, paper or rubber (J. F. Hughes, xe2x80x9cElectrostatics Powder Coatingxe2x80x9d Research Studies, John Wiley and Sons, 1984).
Powder coating resins that are typically employed are epoxy resins, carboxyl- and hydroxyl-containing polyester resins, polyurethane resins and acrylic resins, together with customary hardeners. Combinations of resins are also used. For example, epoxy resins are frequently employed in combination with carboxyl- and hydroxyl-containing polyester resins. Typical hardener components (as a function of the resin system) are, for example, acid anhydrides, imidazoles and also dicyanodiamide and its derivatives, blocked isocyanates, bisacylurethanes, phenolic and melamine resins, triglycidyl isocyanurates, oxazolines and dicarboxylic acids.
In addition, the trans-thiazine-indigo pigments are suitable as colorants in ink-jet inks, both aqueous and non-aqueous, and in those inks which operate in accordance with the hot-melt process.
Based on the substrate to be mass pigmented the thioazine-indigo pigments according to the invention are used in amounts of 0.01 to 30% by weight, preferably 0.1 to 10% by weight.
When applied to the afore-mentioned substrates the thiazine-indigo pigments are found to be resistant to migration and fast to light, and show fastness to washing, chlorite, hypochlorite and peroxide bleaching, rubbing, overspraying and solvents. Notably, the pigments display high tinctorial power, good transparency and good heat stability.